This isnt common for rangers. but i had an old chevy suburban had a problem very similar to that. the power may have something to do wiht the starter. if the solenoid's bad in the starter. no jumpy.

so ask your hubby to check to see if the accesories or any electric (Lights for example.) works. if it DOES. definitly starter. or an electric problem. between the batt. and starter. so its either the starter itself, the wiring, or of course all thats left is the battery. If its the wire setup where the wires screw into the side of the battery. instead of the loops that fit over the main terminal studs. than they can strip out and not make a solid ENOUGH connection.
But whatever the case im SURE itll be one of those 3. so try what mighty tidus suggested. and if it doesnt work after that. your hubby will have to move to the starter as the next cause. good luck. repost if it worked

id liek to know if i helped any :P